JP5932283B2 - Wireless communication apparatus, communication method, and program - Google Patents

Description

  The present invention relates to a wireless communication apparatus, a communication method, and a program for performing communication by switching different directivity patterns formed by an adaptive array antenna.

  Millimeter-wave wireless communication is one of the technologies for realizing high-speed and large-capacity wireless communication. Since the millimeter-wave band has a characteristic that it is highly straight, there is a problem that communication is easily disconnected when a shield such as a human body enters the propagation path. In order to solve this problem, a method of transmitting data using a plurality of different propagation paths between a wireless transmitter and a wireless receiver has been conventionally attempted.

  Patent Document 1 proposes a method of simultaneously receiving a direct wave and one or more reflected waves at an appropriate intensity. According to this method, even when one propagation path is interrupted, radio waves arrive from other propagation paths, so that necessary reception strength can be maintained. However, since radio waves from a plurality of propagation paths are received simultaneously, it becomes a new problem that the influence of frequency selective fading cannot be allowed depending on the installation environment of the wireless transmitter and the wireless receiver.

  As another method, as shown in FIG. 1, in a wireless communication system including a wireless transmitter 110 and a wireless receiver 120 having an adaptive array antenna, signals generated from the same original data are repeated while switching directivity patterns. There is a transmission method. For example, a directivity pattern having a main lobe in the direct wave direction is defined as a first transmission directivity pattern 111 and a first reception directivity pattern 131. In addition, a directivity pattern having a main lobe in a direction in which a radio wave arrives by a single reflection by a reflector 150 such as a wall is defined as a second transmission directivity pattern 112 and a second reception directivity pattern 132. By repeatedly transmitting signals using these two sets of directivity patterns, communication redundancy can be improved.

JP 2000-165959 A

  In such a wireless communication system, a test signal is transmitted prior to data transmission, and the reception intensity is observed. Thereby, the first transmission directivity pattern 111 and the first reception directivity pattern 131, and the second transmission directivity pattern 112 and the second reception directivity pattern 132 can be selected. However, even when a directivity pattern having a main lobe in the direction in which no reflector 150 exists is used, if the side lobe level in the direct wave direction is large, the direct wave can be transmitted and received with sufficiently large power. . Therefore, as shown in FIG. 2, directivity patterns having relatively large side lobes in the direct wave direction may be selected as the second transmission directivity pattern 112 and the second reception directivity pattern 132. Such an event is particularly likely to occur when the distance from the reflector 150 is relatively long and the directional pattern has a main lobe in the direction of the reflector 150 and the reflected wave can be transmitted and received only with relatively small power.

  In this case, communication using the second transmission directivity pattern 112 and the second reception directivity pattern 132 is performed by side lobes in the direct wave direction. Therefore, when a shield enters the direct wave direction, communication using the first transmission directivity pattern 111 and the first reception directivity pattern 131, and the second transmission directivity pattern 112 and the second reception directivity are performed. The problem is that communication in the pattern 132 is interrupted at the same time.

  In addition, directions that can be main lobes are discrete due to time constraints allowed for training of directivity patterns and implementation constraints such as resolution of phase shifters provided in the adaptive array antenna. Therefore, the directional pattern in which the maximum point of the side lobe coincides with the direct wave direction has a higher received power than the directivity pattern in which the local maximum point of the main lobe is closest to the direct wave direction but somewhat deviated There is a case. In this case, contrary to the above-described problem, communication using the first transmission directivity pattern 111 and the first reception directivity pattern 131 is performed with side lobes in the direct wave direction. Furthermore, when the directivity pattern whose local maximum point of the main lobe is closest to the direct wave direction is selected as the second transmission directivity pattern 112 and the second reception directivity pattern 132, two directivity patterns are eventually obtained. Both will communicate using direct waves. For this reason, when a failure occurs in one communication path due to an event such as a direct wave being blocked, communication using two sets of directivity patterns may be interrupted at the same time.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technology that uses a plurality of communication paths with different directivity patterns.

In order to solve the above-described problem, a wireless reception device according to the present invention is a wireless communication device that can communicate with a partner device by switching different directivity patterns formed by antennas, and for wireless communication with the partner device. First selection means for selecting a first directivity pattern used for wireless communication with the counterpart device by transmitting or receiving a signal to each of a plurality of directivity pattern candidates to be used; and For each of a plurality of directional pattern candidates that are different from the directional pattern and that excludes a directional pattern having side lobes in the direction of the main lobe of the first directional pattern. sending or receiving a signal, based on the communication quality of the signal, selecting a second directional pattern used for wireless communication with the partner device Comprising a second selecting means, and communication means for the remote device wireless communication by switching between the first directivity pattern and the second directional pattern.

  According to the present invention, it is possible to reduce the possibility that communication with a plurality of directivity patterns is interrupted, and to improve the reliability of communication.

The block diagram of the conventional radio | wireless communications system. The figure which shows the subject of the conventional radio | wireless communications system. 1 is a configuration diagram of a wireless communication system according to Embodiment 1. FIG. The block diagram of a communication frame. The figure explaining a reception null table. 3 is a flowchart showing the operation of the wireless communication system according to the first embodiment. The sequence diagram which shows the selection operation | movement of the 1st direction for reception. The sequence diagram which shows the selection operation | movement of the 2nd direction for reception. The sequence diagram which shows the confirmation operation | movement of the redundancy of two receiving directivity patterns. The block diagram which shows the structural example of a radio receiver. FIG. 3 is a configuration diagram of a wireless communication system according to a second embodiment. The block diagram which shows the structural example of a wireless transmitter. 10 is a flowchart showing the operation of the wireless communication system according to the third embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<< Embodiment 1 >>
(Wireless communication system)
FIG. 3 is a diagram illustrating a configuration example of a wireless communication system in the present embodiment. The wireless transmitter 110 transmits a plurality of signals generated from the same original data at different times. The plurality of signals are, for example, a signal generated by dividing the original data into a plurality of signals, a signal in which the original data is waveform-formed by changing at least one of the coding rate and the modulation method, or the same signal generated from the original data. Signal. In the following example, two cases will be described, and three or more cases will be described in the third embodiment.

  The wireless receiver 120 forms a plurality of reception directivity patterns (in the example of the figure, two of the first reception directivity pattern 131 represented by a solid line and the second reception directivity pattern 132 represented by a broken line). Then, the above two signals are received. Hereinafter, unless there is confusion, the first reception directivity pattern 131 is referred to as a first directivity pattern 131, and the second reception directivity pattern 132 is referred to as a second directivity pattern 132. Further, the wireless receiver 120 obtains received data by performing predetermined processing on the two received signals. Here, the predetermined processing is, for example, processing for combining data obtained by demodulating two signals, or processing for demodulating after weighting and combining the two signals. The first directivity pattern 131 is a reception directivity pattern that forms a main lobe in the first direction 121. The second directivity pattern 132 is a reception directivity pattern in which a null is formed in the first direction 121 and a main lobe is formed in the second direction 122. Note that the null reception gain and transmission gain need not be completely zero as long as they do not affect the achievement of the desired communication quality.

  Note that the wireless transmitter 110 and the wireless receiver 120 are descriptions for clarifying that they are counterparts of communication. Actually, both the wireless transmitter 110 and the wireless receiver 120 are included in one wireless communication device. These functions may be provided. Further, the wireless communication apparatus may include only one of the wireless transmitter 110 and the wireless receiver 120.

(Composition of communication frame)
Next, a configuration example of a communication frame in the present embodiment will be described with reference to FIG. The wireless transmitter 110 transmits the frames 401 to 403 in time slots assigned according to a predetermined standard. The frames 401 to 403 are configured by a first subframe 411 and a second subframe 412. The first subframe 411 and the second subframe 412 are configured by signals generated from the same original data. The wireless receiver 120 receives the first subframe 411 with the first directivity pattern 131 and receives the second subframe 412 with the second directivity pattern 132. Note that a guard time is set between the first subframe 411 and the second subframe 412 in consideration of the switching time between the first directivity pattern 131 and the second directivity pattern 132 in the radio receiver 120. It may be provided. A plurality of subframes may be prepared according to the number of reception directivity patterns to be used. Also, prepare a normal directivity pattern and a preliminary directivity pattern. If communication quality of the normal directivity pattern deteriorates, use the preliminary directivity pattern for communication. It is not necessary to divide into subframes.

(Reception null table)
Next, the reception null table 500 provided in the wireless receiver 120 of this embodiment will be described with reference to FIG. The reception null table 500 is a table for managing a range set to null when the second directivity pattern 132 is determined. When radio receiver 120 controls directivity in the vertical direction and the horizontal direction, reception null table 500 is a two-dimensional table in the vertical direction and the horizontal direction. Further, when the radio receiver 120 controls the directivity of only one of the vertical direction and the horizontal direction, the reception null table 500 may be a one-dimensional table.

  The reception null range 510 is set when the second direction 122 for reception is selected or when the second direction 122 is reselected. The second directivity pattern 132 is defined as a reception directivity pattern that forms a null in the reception null range 510 and has a main lobe in the second direction 122.

(Configuration of wireless receiver)
FIG. 10 is a block diagram illustrating a configuration example of the wireless receiver 120 of the present embodiment. The reception adaptive array antenna 1001 is a reception unit that receives a radio signal by changing a reception directivity pattern, and outputs the received radio signal to the reception PHY 1002. The reception adaptive array antenna 1001 may have a beam forming control unit (not shown) for variably controlling the reception directivity pattern. Further, the role of the beam forming control unit may be played by a later-described receiver control unit 1004. The reception PHY 1002 is a functional block that performs physical layer signal processing to demodulate the signal input from the reception adaptive array antenna 1001 to obtain reception data. The received data is output to the receiver-side external interface 1003. The receiver-side external interface 1003 converts the reception data input from the reception PHY 1002 into an appropriate format and outputs the converted data to an external device connected to the wireless receiver 120. The receiver control unit 1004 controls the overall operation of the wireless receiver 120. The reception state observation unit 1005 observes the reception state (S710 to S712) of the first training signal and the reception state (S810 to S812) of the second training signal. The receiver-side RAM 1006 temporarily stores parameters and data. The reception null table 500 is stored in the receiver RAM 1006. The receiver ROM 1007 stores the program of the wireless receiver 120 and nonvolatile parameters.

ｗ_kはｋ番目のアンテナ素子のアンテナウェイトである。ｋ番目のアンテナ素子で受信した信号にアンテナウェイトｗ_kが乗算することにより、受信信号の振幅と位相を制御する。 (Reception directivity pattern determination method)
Next, an example of a method for forming the second directivity pattern 132 in the present embodiment will be described. The antenna weight vector W is defined by the following equation, where K is the number of antenna elements of the adaptive array antenna.

w _k is the antenna weight of the k-th antenna element. The signal received by the k-th antenna element is multiplied by the antenna weight w _k to control the amplitude and phase of the received signal.

ｖ_k(θ,φ)はｋ番目のアンテナ素子のアレイ応答である。ｖ_k(θ,φ)の振幅および位相は、アダプティブアレイアンテナから水平方向にθ、垂直方向にφの方向から到来した電波の基準点とｋ番目のアンテナ素子での振幅差と位相差をそれぞれ表す。 Further, the array response vector V is defined by the following equation in consideration of element directivity.

v _k (θ, φ) is an array response of the k-th antenna element. The amplitude and phase of v _k (θ, φ) are the difference in amplitude and phase at the reference point of the radio wave arriving from the adaptive array antenna in the horizontal direction θ and in the vertical direction φ and the kth antenna element, respectively. Represent.

ただし、ＲはＫ行Ｋ列の行列であり、そのｉ行ｊ列成分は次式で定義される。

ここで

は、関数ｆ(θ,φ)の受信ヌル範囲５１０における数値積分を意味し、ｆ^*(θ,φ)は関数ｆ(θ,φ)の複素共役を意味する。 At this time, the antenna weight vector W forming the second directivity pattern 132 is given as an eigenvector corresponding to the maximum eigenvalue of the following matrix X, for example.

However, R is a matrix of K rows and K columns, and its i row and j column components are defined by the following equations.

here

Means the numerical integration of the function f (θ, φ) in the reception null range 510, and f ^* (θ, φ) means the complex conjugate of the function f (θ, φ).

ここで、σは正の実数であり、受信ヌル範囲５１０からの受信電力の大きさに影響するパタメータである。σを大きい値に設定するほど、受信ヌル範囲５１０からの受信電力は大きくなる。 If I is a unit matrix of K rows and K columns, N is defined by the following equation.

Here, σ is a positive real number, and is a parameter that affects the magnitude of the reception power from the reception null range 510. As σ is set to a larger value, the received power from the received null range 510 increases.

ここで、Ｚ^Hは行列Ｚの複素共役転置行列を意味する。 Further, if the vertical component in the second direction 122 is θ ₂ and the horizontal component is φ ₂ , S is defined by the following equation.

Here, Z ^H means a complex conjugate transpose matrix of the matrix Z.

ただし、疑似雑音電力は上述のσの値である。 The second directivity pattern 132 defined in the above example is a directivity pattern that maximizes the next evaluation function g.

However, the pseudo noise power is the value of σ described above.

  If the reception power in the second direction 122 is large enough to achieve the desired communication quality and the reception power from the reception null range 510 is small, an eigenvector corresponding to the eigenvalue that is the second largest after X is an antenna. The weight vector W may be used.

(Operation of wireless communication system)
Next, the operation of the wireless communication system in the present embodiment will be described with reference to FIG. First, the reception first direction 121 is selected from a plurality of first reception direction candidates (S601). Here, the selection operation in the first direction 121 for reception will be described with reference to FIG. Note that the number of first reception direction candidates is A, and the first reception direction candidates are represented as a ₁ , a ₂ ,..., _{A A} , respectively.

  The wireless transmitter 110 continuously transmits the first training signal (S710 to S712). In addition, after the transmission of one first training signal is completed, the next first training signal may be transmitted continuously, or the next first training signal is transmitted after a predetermined time interval. You may make it do.

Wireless receiver 120 form a reception directivity pattern having a main lobe in a ₁ direction (S700), receiving a first training signal (S710). Similarly, the wireless receiver 120 form a reception directivity pattern having a main lobe in a ₂ direction (S701), receiving a first training signal (S711). Similarly, the radio receiver 120 forms a directivity pattern having a main lobe in the direction of each of a _{1 to} a _A (S700 to S702), and receives the first training signal (S710 to S710). S712). The first training signal may be, for example, a signal compliant with IEEE 802.15.3c AV / PHY HRP Preamble.

  When the first training signal is received for all the candidates for the first reception direction, the wireless receiver 120 sets the reception direction in which the communication quality (signal reception quality) of the first training signal is the best. 1 direction 121 is selected (S720). For example, the wireless receiver 120 selects the reception direction in which the reception intensity is maximum as the first direction 121 for reception. When completing the selection of the first direction 121, the wireless receiver 120 notifies the wireless transmitter 110 to that effect (S721). Here, for the notification of selection completion of the first reception direction, it is preferable to use a communication method that does not require training for directivity control. For example, even if IEEE 802.15.3c AV / PHY LRP is used. Good. As described above, first, a plurality of reception directivity patterns are formed in a state where it is not necessary to form nulls in any direction, and a pattern that can obtain the best communication quality is selected from the patterns. This makes it possible to determine a reception direction that can ensure the best communication quality, for example, the arrival direction of a direct wave. In this description, the reception direction with the best communication quality is selected as the first direction 121 for reception. However, one of the reception directions exceeding a predetermined threshold among the communication qualities capable of wireless communication is selected. You may choose. That is, for example, for all candidates in the first reception direction, it is checked whether the communication quality exceeds a predetermined threshold, and the first direction 121 for reception is determined from candidates that exceed the threshold. Also good.

Returning to FIG. 6, following S601, the second direction 122 is selected from a plurality of second reception direction candidates (S602). Here, the selection operation in the second direction 122 will be described with reference to FIG. It is assumed that the number of candidates for the second reception direction is B, and the candidates for the second reception direction are b ₁ , b ₂ ,..., B _B , respectively. In addition, the vertical component in the first direction 121 is represented as θ ₁ and the horizontal component is represented as φ ₁ .

The wireless receiver 120 sets the first direction 121 and its periphery to the reception null range 510 (S800). For example, the radio receiver 120 sets the vertical range of the receiving null range 510 and _{θ 1 -d v / 2~θ 1 +} d v / 2. The radio receiver 120 sets the horizontal range of the received null range 510 and _{φ 1 -d h / 2~φ 1 +} d h / 2. Here, d _v and d _h are parameters that determine the width of the null in the vertical direction and the horizontal direction, respectively.

  The wireless transmitter 110 continuously transmits the second training signal (S810 to S812). In addition, after the transmission of one second training signal is completed, the next second training signal may be transmitted continuously, or the next second training signal is transmitted after a predetermined time interval. You may make it do.

The radio receiver 120 forms a reception directivity pattern having a main lobe in the b ₁ direction under the condition that the reception null range 510 is null (S801), and receives the second training signal (S810). Similarly, the wireless receiver 120, under the condition that the received null range 510 and null, b ₂ direction to form a transmission directivity pattern having a main lobe (S802), receives a second training signal ( S811). Similarly, the radio receiver 120 forms a reception directivity pattern having a main lobe in the direction for each of b _{1 to} b _B under the condition that the reception null range 510 is null (S801 to S801). S803). Then, the wireless receiver 120 receives the second training signal with the formed reception directivity pattern (S810 to S812). The second training signal may be, for example, a signal conforming to IEEE 802.15.3c AV / PHY HRP Preamble.

  When the second training signal is received for all the second reception direction candidates, the wireless receiver 120 selects the direction in which the reception state of the second training signal is the best as the second direction 122. (S820). For example, the radio receiver 120 selects the reception direction in which the reception intensity is maximized as the second direction 122 and selects a directivity pattern having a main lobe in the second direction 122 as the second directivity pattern. . When the selection of the second direction 122 is completed, the wireless receiver 120 notifies the wireless transmitter 110 to that effect (S821). Here, for the notification of selection completion in the second direction 122, it is preferable to use a communication method that does not require training for directivity control. For example, even if IEEE 802.15.3c AV / PHY LRP is used. Good. As described above, in S602, the second training signal is received for a plurality of reception directivity patterns having nulls in the reception direction selected earlier, and the one that can ensure the best communication quality is selected. As a result, it is possible to reliably select a reception directivity pattern having no side lobe in the previously selected reception direction. Further, by using the reception directivity pattern, a signal that can obtain the best communication quality among signals received through a communication path other than the communication path corresponding to the previously selected reception direction is identified and communicated. It can be performed. As a result, communication can be continued even if some of the plurality of communication paths are blocked. In this description, the reception directivity pattern having the best communication quality is selected from the plurality of reception directivity patterns having null in the reception direction selected earlier. One of the reception directivity patterns exceeding a predetermined threshold may be selected. That is, for example, for all candidates in the second reception direction, it is checked whether the communication quality exceeds a predetermined threshold value, and the second direction 122 for reception is determined from candidates that exceed the threshold value. Also good.

  Returning to FIG. 6, following S602, the redundancy of the first directivity pattern 131 and the second directivity pattern 132 is confirmed (S603). If it is determined that the redundancy is insufficient as a result of confirmation in S603, the second direction 122 for reception is reselected. Here, the redundancy confirmation operation of the two reception directivity patterns will be described with reference to FIG.

  The wireless transmitter 110 transmits a redundancy check signal (S911). The redundancy check signal (S911) is, for example, a signal compliant with IEEE 802.15.3c AV / PHY HRP Preamble. The redundancy check is to check whether a plurality of communication paths can be secured with the communication partner.

The wireless receiver 120 forms a reception directivity pattern having a main lobe in the first direction 121 under the condition that the periphery of the second direction 122 is null (S901), and receives a redundancy check signal. (S911). For example, when the second direction 122 in the vertical direction is θ ₂ , the null range of the reception directivity pattern in the vertical direction is θ ₂ −d _v / ₂ to θ ₂ + d _v / 2. Similarly, when the horizontal second direction 122 is φ ₂ , the null range of the horizontal reception directivity pattern is φ ₂ −d _h / ₂ to φ ₂ + d _h / 2. Under this condition, a reception directivity pattern having a main lobe in the first direction 121 is formed. That is, a reception directivity pattern having a main lobe in one of the selected directions for reception (first direction 121) and null in the other selected direction (second direction 122) is formed. .

  The radio receiver 120 compares the communication quality of the redundancy check signal with a predetermined predetermined quality, and whether or not the predetermined quality is exceeded, that is, whether the redundancy is sufficient or insufficient. Is confirmed (S920). For example, if the communication quality exceeds a predetermined threshold, it is determined that the redundancy is sufficient, and if not, it is determined that it is insufficient. Then, the wireless receiver 120 notifies the wireless transmitter 110 of the redundancy determination result (S921). In the notification of the redundancy judgment result, it is preferable to use a communication method that does not require training for directivity control, and for example, IEEE 802.15.3c AV / PHY LRP may be used. In the present embodiment, this redundancy check is performed because the communication quality may not be satisfied if a null is formed in the second direction 122 in the reception directivity pattern having the main lobe in the first direction 121. Is. In the redundancy check, as described above, when a reception directivity pattern having a main lobe in a direction other than the last selected direction and having nulls in other directions including the last selected reception direction is used. Inspect and confirm the communication quality of the signal. If the communication quality satisfies a predetermined quality, it is possible to receive signals that have passed through different reception paths in the selected directions. In this way, all of the selected directions are inspected, and by forming and communicating with a directivity pattern that has obtained a communication quality of a predetermined quality or higher by inspection, some of the plurality of reception paths are disconnected. Even in this case, communication can be continued.

If the wireless transmitter 110 is notified in S921 that the redundancy is insufficient, it starts reselecting the second direction 122 for reception (S902). For example, to perform reselection in the second direction 122, the wireless transmitter 110 starts transmitting a second training signal. Here, in the reselection of the second direction 122, the first direction 121 or its periphery and the second direction 122 or its periphery may be reset as the reception null range 510 in S800 of FIG. For example, θ ₁ −d _v / 2 to θ ₁ + d _v / 2 and θ ₂ −d _v / 2 to θ ₂ + d _v / 2 may be set as the reception null range 510 in the vertical direction. Similarly, φ ₁ −d _h / 2 to φ ₁ + d _h / 2 and φ ₂ −d _h / 2 to φ ₂ + d _h / 2 may be set as the reception null range 510 in the horizontal direction. Thereby, the directivity pattern candidates can be re-formed so that the last selected direction is not re-selected.

  In addition, in the first selection, a plurality of candidates for the reception directivity pattern in which the periphery of the first direction 121 is set as the reception null range 510 is stored, and candidates for which redundancy is insufficient are selected again. You may make it exclude from. Thereby, it is possible to prevent a candidate having insufficient redundancy in reselection from being selected again. In this case, the plurality of reception directivity pattern candidates are stored in the storage unit of the wireless receiver 120 until the reception directivity pattern to be used is determined. By storing the antenna weight to be multiplied, a reception directivity pattern candidate can be stored. In addition, the reception directivity pattern candidates are stored in association with information indicating whether the candidates have been selected in the past. This makes it possible to identify candidates for which redundancy has been insufficient in the past. Further, information about candidates whose redundancy is insufficient may be deleted from the storage unit.

  Returning to FIG. 6, when the redundancy check (S603) is completed, the wireless transmitter 110 starts data transmission (S604). The wireless transmitter 110 transmits frames 401 to 403 to the wireless receiver 120. Note that the wireless receiver 120 may reselect one or both of the first direction 121 and the second direction 122 for reception after the start of data transmission. In that case, the wireless receiver 120 may notify the wireless transmitter 110 that reselection is performed.

<< Embodiment 2 >>
In the first embodiment, the reception directivity pattern of the wireless receiver is switched for each subframe. In the present embodiment, the transmission directivity pattern of the wireless transmitter is switched for each subframe. The configuration of the communication frame in the present embodiment is the same as that in the first embodiment. This embodiment will be described with reference to FIG.

  FIG. 11 is a diagram illustrating a configuration example of a wireless communication system in the present embodiment. The wireless transmitter 110 transmits two transmission signals generated from the same original data in the first subframe 411 and the second subframe 412 respectively. The wireless transmitter 110 transmits the first subframe 411 using the first transmission directivity pattern 111 and transmits the second subframe 412 using the second transmission directivity pattern 112.

  The first transmission directivity pattern 111 is a directivity pattern that forms a main lobe in the first direction 101 for transmission. The second transmission directivity pattern 112 is a directivity pattern in which a null is formed in or around the first direction 101 and a main lobe is formed in the second direction 102 for transmission. The second transmission directivity pattern 112 is formed by using an eigenvector corresponding to the maximum eigenvalue of X defined by (Equation 3) as an antenna weight, for example, as in the first embodiment.

  As in the first embodiment, the wireless receiver 120, which is a communication counterpart device of the wireless transmitter 110, obtains received data by performing predetermined processing on the two received signals. Similarly to the first embodiment, the wireless receiver 120 may receive the first subframe 411 using the first directivity pattern 131 and receive the second subframe 412 using the second directivity pattern 132. Good.

  The first direction 101 for transmission is selected from a plurality of candidates for the first direction for transmission. For example, in the same manner as in FIG. The wireless transmitter 110 continuously transmits the first training signal in a transmission directivity pattern in which each of the plurality of candidates in the first direction for transmission is a main lobe (S710 to S712). The wireless receiver 120 selects the transmission direction of the first training signal with the best reception state as the first direction 101 and notifies the wireless transmitter 110 of the selected first direction 101 for transmission. When the wireless receiver 120 does not know the transmission direction of the first training signal, the wireless receiver 120 counts the number of received first training signals, and the first training signal with the best reception state is received. The wireless transmitter 110 may be notified of whether or not In this way, first, the first direction 101 for transmission that can ensure the best communication quality, such as the direct wave direction, is selected in a state where there is no restriction to form a null. As a result, for example, it is possible to determine a transmission direction that is normally used between the wireless transmitter 110 and the wireless receiver 120 that is a communication counterpart device. Note that it is not necessary to select a case where the communication quality is not the best, and a transmission direction satisfying a predetermined quality may be selected as the first direction 101 for transmission. That is, whether or not the communication quality exceeds the predetermined quality is checked for all the transmission direction candidates, and the first direction 101 for transmission is selected from the transmission directions in which the communication quality exceeds the predetermined quality. Good.

  The radio receiver 120 may use the first directivity pattern 131 and the second directivity pattern 132. In this case, the reception state of the first training signal is observed for all pairs of the first direction candidate for transmission and the first reception direction candidate (S710 to S712). Then, the transmission direction and the reception direction with the best communication quality are selected as a pair of the first direction 101 for transmission and the first direction 121 for reception. Note that it is not necessary to select a case where the communication quality is not the best, and the transmission direction and the reception direction satisfying the predetermined quality are a pair of the first direction 101 for transmission and the first direction 121 for reception. You may choose. That is, for all the candidates for the pair of the transmission direction and the reception direction, it is checked whether the communication quality exceeds a predetermined quality, and the first direction for transmission is selected from the pairs whose communication quality exceeds the predetermined quality. A pair of 101 and the first direction 121 for reception may be selected.

  The second direction for transmission 102 is selected from a plurality of candidates for the second direction for transmission. For example, in the same manner as in FIG. The wireless transmitter 110 sets the first direction 101 for transmission and the vicinity thereof to the transmission null range. Further, the wireless transmitter 110 continuously outputs the second training signal with a transmission directivity pattern having each of the candidates for the second direction for transmission as the main lobe under the condition that the transmission null range is null. It transmits (S810-S812). The wireless receiver 120 selects the transmission direction of the second training signal with the best reception state as the second direction 102 and notifies the wireless transmitter 110 of the selected second direction 102 for transmission. When the wireless receiver 120 does not know the transmission direction of the second training signal, the wireless receiver 120 counts the number of received second training signals, and the second training signal with the best reception state is received. The wireless transmitter 110 may be notified of whether or not In this way, a plurality of transmission directivity patterns having nulls in the previously selected transmission direction are selected so that the wireless communication device 120 that is the counterpart device can ensure the best communication quality. Thereby, it is possible to reliably select a transmission directivity pattern having no side lobe with respect to the previously selected transmission direction. Further, by using the transmission directivity pattern, communication is performed by identifying signals that can be obtained through the communication path other than the communication path corresponding to the previously selected reception direction and that can obtain the best communication quality. It can be performed. As a result, communication can be continued even if some of the plurality of communication paths are blocked.

  In addition, when using the first directivity pattern 131 and the second directivity pattern 132, the wireless receiver 120 uses all of the candidates for the second direction for transmission and the candidates for the second direction for reception. The reception state of the second training signal is observed for the pair (S810 to S812). Then, the transmission direction and the reception direction with the best reception state are selected as a pair of the second direction for transmission 102 and the second direction 122 for reception. Note that it is not necessary to select a case where the communication quality is not the best, and a transmission direction and a reception direction satisfying the predetermined quality are set as a pair of the second direction for transmission 102 and the second direction 122 for reception. You may choose. That is, it is checked whether the communication quality exceeds a predetermined quality for all the transmission direction and reception direction pair candidates, and the second direction for transmission is selected from the pairs whose communication quality exceeds the predetermined quality. A pair of 102 and the second direction 122 for reception may be selected.

  After the selection of the first direction 101 for transmission and the second direction 102 for transmission is completed, the redundancy of the first transmission directivity pattern 111 and the second transmission directivity pattern 112 is confirmed. As a result, when it is determined that the redundancy is insufficient, the second direction 102 for transmission is reselected. The redundancy check is executed as follows, for example, in the same manner as in FIG.

  The wireless transmitter 110 forms a transmission directivity pattern having a main lobe in the first direction 101 for transmission under the condition that the periphery of the second direction 102 for transmission is null, and a redundancy check signal Is transmitted (S911). The wireless receiver 120 compares the communication quality of the redundancy check signal with a predetermined threshold and determines whether the redundancy is sufficient or insufficient (S920). If it is determined that the redundancy is insufficient, the periphery of the first direction 101 for transmission and the periphery of the second direction for transmission before reselection are set as the transmission null range, and the directivity pattern is set. Then, the second direction 102 for transmission is selected again (S902).

  When the wireless receiver 120 uses the first directivity pattern 131 and the second directivity pattern 132, for example, in the first direction 121 for reception that is a pair of the first direction 101 for transmission. A reception directivity pattern having a main lobe is formed to confirm redundancy. In this case, a null is formed in the reception direction 122 that is a pair of the second direction 102 for transmission. When it is determined that the redundancy is insufficient, the second direction 102 for transmission and the second direction 122 for reception are reselected.

  In the present embodiment, this redundancy check is performed when a null is formed in the second direction for transmission in the transmission directivity pattern having the main lobe in the first direction 101 for transmission. This is executed because the communication quality may not be satisfied in the device 120. In the redundancy check, as described above, a transmission directivity pattern having a main lobe in a transmission direction other than the last selected transmission direction and null in other transmission directions including the last selected transmission direction is used. The communication quality of the signal in the wireless receiver 120 is confirmed. If the communication quality satisfies the predetermined quality, the signal transmitted from each of the selected transmission directions can be received by the wireless receiver 120 via different paths, and some of the multiple paths are disconnected. Communication can be continued.

  FIG. 12 is a block diagram illustrating a configuration example of the wireless transmitter 110 in the wireless communication system of the present embodiment. The transmitter-side external interface 1203 converts transmission data input from an external device connected to the wireless transmitter 110 into an appropriate format, and outputs the converted data to the transmission PHY 1202. The transmission PHY 1202 modulates an input signal from the transmitter-side external interface 1203 and outputs the modulated signal to the transmission adaptive array antenna 1201. The transmission adaptive array antenna 1201 transmits the signal input from the transmission PHY 1202 by changing the transmission directivity pattern. Note that the transmission adaptive array antenna 1201 may include a beam forming control unit (not shown) for performing variable control of the transmission directivity pattern. Further, the function of the beam forming control unit may be performed by a transmitter control unit 1204 described later. The transmitter control unit 1204 controls the overall operation of the wireless transmitter 110. The transmitter RAM 1205 temporarily stores parameters and data. A transmission null table used to determine the second direction for transmission is configured in the transmitter RAM 1205. The transmitter-side ROM 1206 stores programs for the wireless transmitter 110 and nonvolatile parameters.

<< Embodiment 3 >>
In the first embodiment and the second embodiment, the wireless receiver and / or the wireless transmitter transmits data with two directivity patterns. In the present embodiment, a case where data is transmitted with a plurality (M (M> 2)) directivity patterns will be described. In order to simplify the description, a case where directivity control is performed only by the wireless receiver 120 will be described. It is apparent from the second embodiment that the directivity pattern can be similarly established when directivity control is performed only by the wireless transmitter 110 and when directivity control is performed by both the wireless receiver 120 and the wireless transmitter 110. is there.

  The wireless transmitter 110 transmits M signals generated from the same original data at different times (M> 2). Here, the m-th transmitted signal is called a subslot m (1 ≦ m ≦ M). The radio receiver 120 forms a reception directivity pattern having a main lobe in the m-th direction under the condition that the first to (m-1) -th directions for reception or the vicinity thereof are null, and sets the subslot m to Receive. Such a directivity pattern can be formed, for example, by using an eigenvector corresponding to the maximum eigenvalue of X defined by (Equation 3) as an antenna weight, as in the first embodiment.

  FIG. 13 is a diagram illustrating an example of a flow of the wireless communication system in the present embodiment. First, as in the first embodiment, the first directivity pattern 131 is selected, the second directivity pattern 132 is selected, and the redundancy of the first directivity pattern 131 and the second directivity pattern 132 is selected. Are confirmed (S601 to S603). If it is determined that the redundancy is insufficient, the second direction 122 for reception is reselected.

  Subsequently, the wireless receiver 120 selects the m-th reception directivity as follows (S1301). Here, it is assumed that the wireless transmitter 110 continuously transmits the m-th training signal. The wireless receiver 120 generates a reception directivity pattern in which each of the candidates in the m-th direction for reception is a main lobe under the condition that the first to m-1th directions for reception or the vicinity thereof are null. Forming and receiving the mth training signal. Then, the mth direction for reception is selected based on the reception state of the mth training signal.

  After selecting the m-th direction for reception, the wireless receiver 120 checks the redundancy of the first to m−1 reception directivity patterns 131 and the m-th reception directivity pattern as follows ( S1302). Note that the wireless transmitter 110 repeatedly transmits a redundancy check signal m−1 times. This forms a reception directivity pattern having a main lobe in each of the first to m-1 directions for reception while forming a null in or around the mth direction for reception, and for each of the patterns This is because redundancy is checked. The radio receiver 120 forms a reception directivity pattern having a main lobe in the first direction 121 while forming nulls in the second to m directions for reception or in the vicinity thereof, similarly to S911 in FIG. The first redundancy check signal is received. Similarly, receiving directivity having a main lobe in the l-th direction (1 ≦ l ≦ m−1) while forming nulls in or around the first to l−1 and l + 1 to m directions for reception. A pattern is formed and the first redundancy check signal is received. The wireless receiver 120 compares the reception state of the redundancy check signal received m-1 times with a predetermined threshold value, and determines whether the redundancy is sufficient or insufficient. If it is determined that the redundancy is insufficient even once, the first to m directions for reception or its surroundings and the mth direction or its surroundings before reselection are reset as reception null ranges. The directivity pattern is reformed and the m-th direction, that is, the last selected direction is reselected. Thereafter, the same procedure is repeated to determine the first to Mth reception directivity patterns, and data transmission is performed using the reception directivity patterns (S1303).

  In this way, a large number of paths can be used, and communication can be continued even if some of the available paths are cut off by a shield or the like. It should be noted that the null reception gain and transmission gain described in each of the above embodiments need not be completely zero as long as they do not affect the achievement of the desired communication quality. Similarly, the reception power of the main lobe may not be the maximum in the directivity pattern as long as the reception gain and the transmission gain of the main lobe are large enough to have no influence on achieving the desired communication quality.

  In addition, the above description is an example of embodiment of this invention, and it cannot be overemphasized that this invention is not necessarily limited to this embodiment.

<< Other Embodiments >>
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (11)

A wireless communication device that can communicate with a partner device by switching different directivity patterns formed by an antenna,
A first directivity pattern used for radio communication with the counterpart device is selected by transmitting or receiving a signal to each of a plurality of directivity pattern candidates used for radio communication with the counterpart device. A selection means;
A plurality of directional pattern candidates each having a directional pattern different from the first directional pattern and excluding directional patterns having side lobes in the direction of the main lobe of the first directional pattern. A second selection means for transmitting or receiving a signal and selecting a second directivity pattern used for wireless communication with the counterpart device based on the communication quality of the signal ;
Communication means for performing wireless communication with the counterpart device by switching between the first directivity pattern and the second directivity pattern;
A wireless communication apparatus comprising: The first selection unit selects the first directivity pattern based on communication quality of a signal transmitted or received for each of a plurality of directivity pattern candidates.
The wireless communication apparatus according to claim 1. The first selection means selects, as the first directivity pattern, a directivity pattern having the best communication quality of a signal transmitted or received for each of a plurality of directivity pattern candidates.
The wireless communication apparatus according to claim 2. The first selection means selects, as the first directivity pattern, a directivity pattern in which the communication quality of a signal transmitted or received for each of a plurality of directivity pattern candidates exceeds a predetermined threshold value.
The wireless communication apparatus according to claim 2. The first selecting means reselects the first directivity pattern based on the communication quality of the signal transmitted or received by the second directivity pattern selected by the second selecting means;
The wireless communication device according to claim 1, wherein the wireless communication device is a wireless communication device. The second selection means selects, as the second directivity pattern, a directivity pattern having the best communication quality of a signal transmitted or received for each of a plurality of directivity pattern candidates.
The wireless communication apparatus according to claim 1 . The second selection means selects, as the second directivity pattern, a directivity pattern in which the communication quality of a signal transmitted or received with respect to each of a plurality of directivity pattern candidates exceeds a predetermined threshold value.
The wireless communication apparatus according to claim 1 . In the second selection means, a plurality of directional pattern candidates from which directional patterns having side lobes in the main lobe direction of the first directional pattern are excluded are the first directional pattern candidates. A directional pattern with a null in the direction of the main lobe,
The wireless communication apparatus according to any one of claims 1 7, characterized in that. The signal transmitted or received by the first selection means and the second selection means is a training signal.
The wireless communication apparatus according to any one of claims 1 8, characterized in that. A communication method in a wireless communication device that can communicate with a partner device by switching different directivity patterns formed by an antenna,
A first directivity pattern used for radio communication with the counterpart device is selected by transmitting or receiving a signal to each of a plurality of directivity pattern candidates used for radio communication with the counterpart device. A selection process;
A plurality of directional pattern candidates each having a directional pattern different from the first directional pattern and excluding directional patterns having side lobes in the direction of the main lobe of the first directional pattern. In contrast, a second selection step of transmitting or receiving a signal and selecting a second directivity pattern used for wireless communication with the counterpart device based on the communication quality of the signal ;
A communication step of performing wireless communication with the counterpart device by switching between the first directivity pattern and the second directivity pattern;
A communication method characterized by comprising: The program for functioning a computer as each means with which the radio | wireless communication apparatus of any one of Claim 1 to 9 is provided.

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